Auto Gearbox Fault

[rich.g.williams]

just one thing - be sure not to turn ignition on with pilot bush connector disconnected because it will throw up error codes that need a STAR machine to reset

 

[Striker]

Saturday 12/12/09

I disconnected battery, removed the pilot bush plug from gearbox, cleaned the contact pins with switch cleaner as they were a bit oily & dirty. No trace of ATF leaking out from this.

Inspected the 2 multi plugs that go into ETC control unit these were found to be contaminated with wax oil, as last summer i sprayed wax oil under the wheel arch & inner wings (wheel arch cover removed). Not sure how this got into the N/S/F footwell but the wax oil tracked up the cables & on to the ETC multi plug pins. No trace of any water ingress. Cleaned those with switch cleaner, allowed to dry then re-connected.
Gearbox was working correctly for 48hrs & after covering 50ish miles & 6 separate journeys. Then on Monday 14th, it decided to stick in 3rd gear again after covering 11 miles of a 21 mile journey. This cleared after a re start

Wednesday 16/11/09

Had codes read at local indie with STAR (gearbox not gone faulty since Monday 14th)

Here are the fault codes-

P 2502 The gear is implausible or the transmission is slipping-Stored

P 2203 The internal electric check of component Y3/6N3 (speed sensor 3 has failed)

P 2001 Component N15/3 (ETC EGS) control unit is defective.

Any comments or explanations regarding these fault codes would be welcome.

My local indie has recommended a local auto gearbox specialist, whom i have spoken to and hopefully will be taking my car in Fri or Mon.

 

[rich.g.williams]

don't like the sound of the P2001 - could be Waxoyl induced?

the P2203 well that's a speed sensor on the electroplate, sounds like it might not be too much of a drama

 

[Striker]

don't like the sound of the P2001 - could be Waxoyl induced?

And i thought i was doing a good bit of preventative maintenance with the waxoyl! Saying that the waxoyl didnt penetrate into the ETC, only onto the back of the multi plugs. If the ETC was `defective` as star says, would it not work at all?
Im praying it isnt this. I`ll post further information after the auto transmission specialist has had a look.

 

[rich.g.williams]

don't really think that Waxoyl would cause a bad contact or a short circuit, the two connectors onto the ETC computer are high quality

the ETC has been controlling the gearbox fully for you recently and they are built to a very high standard. It diagnoses itself so it could be finding an internal error and still be working but it could be a stored one off event because the battery was flat or something agree start praying

the speed sensor well that will put it into limp mode.

don't like the P2502 I get that and not solved yet

clear all error codes, run car until it goes into limp mode then read error codes again to see what's come up, if its the speed sensor again you have a clue

 

[Striker]

Quote `don't like the P2502 I get that and not solved yet`

I dont get it either Richard. The `P 2502 The gear is implausible or the transmission is slipping` The gear maybe implausible but my transmission is not slipping even with 4 adults in car traveling up a steep hill!

Andy.

 

[rich.g.williams]

Andy,

Apparently the ETC computer calculates the current gear engaged and compares it to the intended gear. If the speed sensor is faulty the calculated gear is "implausible" hence the P2502 error code.

Nice explanation but it hasn't helped me yet.

If your transmission works 100% on a good day with no slip - that's a bit of good news.

 

[Striker]

Andy,

Apparently the ETC computer calculates the current gear engaged and compares it to the intended gear. If the speed sensor is faulty the calculated gear is "implausible" hence the P2502 error code.

Nice explanation but it hasn't helped me yet.

If your transmission works 100% on a good day with no slip - that's a bit of good news.

Thats what im hoping!
Read your thread `P0730 Incorrect Gear Ratio` I admire your knowledge and perseverance with it. It would be interesting & probably eye watering to know how much ££££`s a MB dealer would charge to fix it!.

 

[Alex Crow]

the p2203 points straight to the electroplate. don't worry about the p2001, i have seen this loads of times but never had to change an etc module yet! and the p2502 PROBALY backs up the p2203 - at least in this case (hello rich )

 

[Striker]

I`ll let you know the outcome after cars been to the auto trans specialist.

 

[Alex Crow]

a full rebuild, circa £2,000. but then i AM a cynic :roll:

 

[rich.g.williams]

Andy,

Thanks your kind comments. I think you are lucky because a specific speed sensor fault is sometimes there, when its not there your gearbox is working 100% normally.

and the p2502 PROBALY backs up the p2203 - at least in this case (hello rich)

Alex,

Really do think that MB should publish more information as to what conditions the ETC tests so as to flag its various error codes - especially something like P2502

I did come across this about P2502:-

 

[Striker]

Just spoke to the Auto Transmission specialist & car booked in Friday (tomorrow)
.
From the fault i have described, he said it could be the electroplate or a problem with the valve assembly.

He said something about performing a hydraulic pressure test, as when certain parts in the G/box are worn, ATF pressure drops, causing intermittent slipping & limp mode

Hes got 2 mercs in at the moment with same symptoms as mine (722.6 box)
I will post results of the faulty part(s) and what work is required, in due course

 

[rich.g.williams]

the working pressure is controlled by a regulator valve and this in turn is controlled by the modulating solenoid, its possible for wear in the working pressure regulator valve bore to allow the modulating pressure to "leak" past there are photos of this wear in my threads and have a look at http://www.sonnax.com/instructions/68942-06-IN.pdf

for my transmission I "decided" that there wasn't enough wear to cause a serious loss of working pressure and anyway working pressure only has to be increased when gear changes occur at medium to high engine torque (to keep the change snappy)

for my box it goes into limp mode especially if gear changes are at low engine torque and fairly low rpm

I'm finding it hard to buy the hydraulic pressure test business but you never know

working pressure could also leak away if there were faulty piston seals etc within the transmission drivetrain but if so you would expect the worst effects of this to occur at engine idle speed, again for my transmission gearshifts at idle are sharp

trouble is it easy to work and work and replace and replace and of course eventually the fault goes away

 

[Striker]

Car now Fixed!

Just got my car back now fully repaired.

Mr. Gearbox, the Transmission specialist did a Glycol test which was positive.
My car dose not have the valeo rad. The ATF cooler on my car is mounted under the oil filter housing (F/N/S or engine block) Apparently this cooler has a double matrix that lets engine coolant curculate through one compartment which had failed, letting glycol into the other compartment of the cooler which contains the Atf. Bad design i say as engine coolant runs optimum temp of 80 to 90c which surely is to hot to cool the atf.

The electroplate & valve body control unit were damaged by the glycol contamination. A new independant ATF cooler was fitted behind the lower front bumper air grill, bypassing the leaking original AtF cooler (where mb should have put it in the first place!)
A gearbox ATF flush was done, then refilled with new atf
The TC appears to be ok.
Total cost (inc Labour) = £830.
A courtasy car was also included in that price.

 

[Number_Cruncher]

>>Bad design i say as engine coolant runs optimum temp of 80 to 90c which surely is to hot to cool the atf.

No, that's perfect.

 

[television]

Not very cheap that repair

 

[Striker]

Not very cheap that repair

I disagree. Cheaper than mb. They quoted £85 for star diagnostics, 4hrs labour@ £85+vat. Then add cost of electoplate + valve body control unit 2 lots of atf (approx 13 litres) Sump gasket + filter, and a new atf cooler which mb wanted £220. for. likley bill over £1100

 

[S.Speed]

Just got my car back now fully repaired.

Mr. Gearbox, the Transmission specialist did a Glycol test which was positive.
My car dose not have the valeo rad. The ATF cooler on my car is mounted under the oil filter housing (F/N/S or engine block) Apparently this cooler has a double matrix that lets engine coolant curculate through one compartment which had failed, letting glycol into the other compartment of the cooler which contains the Atf. Bad design i say as engine coolant runs optimum temp of 80 to 90c which surely is to hot to cool the atf.

The electroplate & valve body control unit were damaged by the glycol contamination. A new independant ATF cooler was fitted behind the lower front bumper air grill, bypassing the leaking original AtF cooler (where mb should have put it in the first place!)
A gearbox ATF flush was done, then refilled with new atf
The TC appears to be ok.
Total cost (inc Labour) = £830.
A courtasy car was also included in that price.

God I have that sort of ATF cooler on mine.. I was being rather smug thinking "No Valeo Probs for me"
It looks like I am not beyond risk after all...
Have to say I am starting to give a third party oil cooler some serious thought..
STRIKER.... Where did you have yours fitted ??

 

[Miffy]

This could be just bad luck instead of a generic bad design ? But I guess if your concerned it may be an issue then its going to be far cheaper to add an external oil cooler now before this affects you.